When using Unity 2021.3.8, I used the URP (12.1.7) version with Spine (4.1.25) packages in Unity and the URP support package (4.1.23). When packing resources from the sample projects "StretchymanURP" and "RaptorURP" into Unity AssetsBundle and loading them through resource updates, the te, the situation shown in the picture below occurred.The test platform is iOS
Encountered a Spine issue with hot-updated AssetBundle loading on iOS
@Qingswe This looks like you're using a straight alpha texture at a Material which is set to PMA (see the documentation FAQ section here).
Please note that the example assets in the URP package use straight alpha textures and materials, while the spine-unity package skeleton assets in Spine Examples use PMA. Likely you're assigning the wrong texture at the wrong material.
We set it as shown in the picture below. How should we set it to display correctly on iOS?
@Qingswe You have incorrectly disabled Alpha is Transparency at the Texture Import settings in the second screenshot. If the texture is a straight-alpha texture, you need to enable both sRGB (Color Texture) and Alpha is Transparency as described in the documentation here:
https://esotericsoftware.com/spine-unity#Advanced---Premultiplied-vs-Straight-Alpha-Import
Or in case you prefer the Chinese page, here is the direct link to the relevant PMA vs Straight Alpha section.
Harald I seem to understand what you mean. As I am using the URP rendering pipeline (so I am currently using "Linear Color Space"), I should uncheck "Pre multiple alpha" and "Bleed" in the Spine Texture wrapper. I have already done this and imported Unity, which is my latest material and image settings.This is the solution that I modified after referring to the runtime documentation, but I also noticed that the material 'spineboy pro Material Additive' has turned pink. Correspondingly, there are also anomalies in the display after loading with 'AssetBundle'
This anomaly seems to be caused by that pink material.There is no material similar to 'Additive' in Spine URP Example, what should I do 
I also encounter with similar issue, on previous version of iOS it's working fine. But since I updated occurs a similar issue...
Qingswe I should uncheck "Pre multiple alpha" and "Bleed" in the Spine Texture wrapper.
No, you should not uncheck both. Where did you get that advice from? Please have a look at the documentation on settings for straight alpha, the image below the heading 2. Straight Alpha shows the correct settings. I've posted the link to the documentation section in my previous posting, please have a look at it again.
but I also noticed that the material 'spineboy pro Material Additive' has turned pink. Correspondingly, there are also anomalies in the display after loading with 'AssetBundle'
If you see pink materials, your assigned shader at the Material is not compatible with the render pipeline or renderer you are using (URP 2D vs 3D renderer), or it contains compile errors (e.g. when include files are missing).
This anomaly seems to be caused by that pink material.There is no material similar to 'Additive' in Spine URP Example, what should I do
Just assign the suitable URP additive shader, either
"Universal Render Pipeline/Spine/Blend Modes/Skeleton Additive" for the normal URP 3D renderer or
"Universal Render Pipeline/2D/Spine/Blend Modes/Skeleton Additive" when using the URP 2D renderer.
If you don't see these shaders, please update your Spine URP Shaders UPM package to the latest 4.1 package.
I should uncheck "Pre multiple alpha" and "Bleed" in the Spine Texture wrapper.
Sorry, this is a clerical error,The correct one is the following sentence 
" I should uncheck "Pre multiple alpha" and check "Bleed" in the Spine Texture wrapper. "
This is a screenshot of my export and the exported file:
spineboy-bleed.zip
1MB
And I fixed the pink material in 'spine-urp', but it still showed white edges
Set the image and material according to the following text
Texture Packer setting Premultiply alpha disabled, Bleed enabled,
Unity Texture settings sRGB (Color Texture) and Alpha Is Transparency enabled,
Unity Material parameter Straight Alpha Texture enabled.
I rebuilt the project and repackaged AssetBundle,But the problem still exists
Qingswe Sorry, this is a clerical error,The correct one is the following sentence
" I should uncheck "Pre multiple alpha" and check "Bleed" in the Spine Texture wrapper. "
This is a screenshot of my export and the exported file:
Thanks for the clarification, glad to hear that it was just the sentence that was wrong 
. That can happen rather easily with such a lot of parameter options.
Qingswe I rebuilt the project and repackaged AssetBundle,But the problem still exists
Sorry to hear your problems persist! Are you sure you've rebuilt the asset bundles for the right platform and that things are really updated? You could have a try replacing the texture with a definitely modified version (e.g. paint red text onto the face or something like that) to see whether your asset modifications end up used in the actual game.
If it's indeed updated correctly, could you please send us a minimal Unity project which still demonstrates this issue? You can send it as a zip package to contact@esotericsoftware.com, briefly mentioning this forum thread URL so that we know the context. Then we can have a look at what's going wrong.
- Editado
Harald
Thank you for pointing out the issue with using Spine in URP, which helped me better understand this software.
My colleagues and I opened AssetBundle in AssetStudio and found that the URP Spine Shader referenced by the resource was incorrect. However, I was able to ensure that my settings were correct in Unity Editor. Therefore, after downloading AssetBundle, I reset the SkeletonDataAsset in the SkeletonAnimation and reassigned the Shader to the Material before reinitializing the animation, I finally got the right result! 
Here is the code for me to download SkeletonDataAsset and Material and reset SkeletonAnimation
SkeletonAnimation skeletonAnimation;
SkeletonDataAsset skeletonDataAsset;
GameObject spineGO;
Material spineMaterial_1;
Material spineMaterial_2;
public void OnEnterFight()
{
GeometryGameObject = Instantiate(GameEntry.Res.GetAsset<GameObject>("Geometry_Geometry").AssetObject as GameObject);
spineGO = GeometryGameObject.FindGameObjbyName("SpineBoy");
skeletonAnimation = spineGO.GetComponent<SkeletonAnimation>();
GameEntry.Res.LoadAsset<SkeletonDataAsset>("bleed_spineboy-pro_SkeletonData", (handle) =>
{
skeletonDataAsset = handle.AssetObject as SkeletonDataAsset;
Log.Debug("Skeleton Download OK");
CheckDownLoad();
});
GameEntry.Res.LoadAsset<Material>("bleed_spineboy-pro_Material", (handle) =>
{
spineMaterial_1 = handle.AssetObject as Material;
spineMaterial_1.shader = Shader.Find("Universal Render Pipeline/Spine/Skeleton");
Log.Debug("mat1 Download OK");
CheckDownLoad();
});
GameEntry.Res.LoadAsset<Material>("bleed_spineboy-pro_Material-Additive", (handle) =>
{
spineMaterial_2 = handle.AssetObject as Material;
spineMaterial_2.shader = Shader.Find("Universal Render Pipeline/Spine/Blend Modes/Skeleton Additive");
Log.Debug("mat2 Download OK");
CheckDownLoad();
});
}
public int count = 0;
private void CheckDownLoad()
{
count++;
if (count==3)
{
skeletonAnimation.skeletonDataAsset = skeletonDataAsset;
skeletonAnimation.Initialize(true);
skeletonAnimation.initialSkinName = "default";
skeletonAnimation.AnimationName = "jump";
}
}But I still haven't figured out what happened, causing the material references in AssetBundle to change inexplicably. As can be seen from the screenshot I provided below, my strategy for packaging AssetBundle is to only package "Prefab" and have it automatically reference the required materials and shaders. Although I have already solved this problem (re assigning and initializing the aforementioned things), But I think this issue may be a Unity issue.
Qingswe My colleagues and I opened AssetBundle in AssetStudio and found that the URP Spine Shader referenced by the resource was incorrect
Could you please describe what exactly was incorrect? That would be interesting to know, and might potentially help others.
It's a pity that the cause of the problem is still not clear. Perhaps it's shader stripping which is removing the variants that you would require. This was also very recently discussed on this thread here:
https://esotericsoftware.com/forum/d/24881-white-seams-when-using-bleed--straight-alpha-with-unity-on-android/31
You could have a try whether it changes anything if you're creating a dummy Material included in your main game (not in an asset bundle) which references the shader in the required shader variant by using the same parameters like Straight Alpha Texture, and so on.
I downloaded Assets Bundle in Unity Editor and loaded it. The Shader name on Material was correct, but the display was incorrect. Therefore, I reassigned the Shader named 'Universal Render Pipeline/Spine/Skeleton' to Material in Inspector, and I found that doing so would restore the display to normal.
When I unpacked Assets Bundle, I found these three shaders that shouldn't have appeared in the bag.
I checked the Spine settings in Unity.
These places have all been replaced by me, but the "Spine/Blend Modes/Skeleton PMA Screen" still exists. Later, I discovered that the Spine in another folder may still be referencing the Shader of a non-URP rendering pipeline. I checked and found that it was not, so I can confirm that the SpineBoy in my scene is indeed using this "Universal Render Pipeline/Spine/Skeleton" Shader, the reason for the display error is likely due to the Shader variant issue you mentioned, so when I reloaded and set SpineBoy, it worked normally.
Qingswe The Shader name on Material was correct, but the display was incorrect.
What exactly did you encounter as "the display was incorrect"? Do you mean that the name is Spine/Blend Modes/.. as seen in your first screenshot, and not (what would be correct) Universal Render Pipeline/Spine/Blend Modes/.. although you assigned the other material?
If this is the case, your first screenshot is indeed strange. It somehow looks like a problem of asset bundle creation having some incorrect cache items, or not rebuilding the bundle properly. Did you try if removing the Library or your build directories helps? You can create a backup of your project first to be on the safe side.
Qingswe the reason for the display error is likely due to the Shader variant issue you mentioned
Do you have the shaders assigned in the Always Included Shaders in Project Settings - Graphics? If so, does it change anything when you remove them from this list?